The present invention relates to devices for loading radioactive seeds and optionally spacers into needles, catheters or other means, prior to administration to a patient.
The treatment of prostrate cancers by brachytherapy, i.e. the permanent implantation of radioactive sources (known as xe2x80x9cseedsxe2x80x9d) into a patient""s body, involves the administration of typically 80-100 seeds per patient in a defined 3-D array. These seeds can be implanted by two different methods. In the first method, known from U.S. Pat. No. 5,242,373, a seed plug is assembled by hand from alternating loose seeds and biodegradable spacers (e.g. made of catgut) picked from a dish. The spacers can have any desired length and are positioned between the seeds in order to give the required separation between the seeds. The assembled plug is then implanted into the patient via a needle. A problem with this method is the person making the plug is exposed to radiation from the loose seeds in the dish and is also exposed to radiation when loading the seeds into the implantation needle. A further disadvantage is that considerable numbers of seeds and spacers have to be handled individually and each configured in the correct orientation to give the desired end-to-end xe2x80x9cplugxe2x80x9d. The seed/spacers are also small e.g. typically 4-6 mm long, and this leads to time-consuming manual handling, with an associated radiation dose hazard. However this method has the advantage that as several seeds can be implanted in the patient at once through using pre-made plugs, the time spent in the operating theatre is reduced and the spatial separation of the seeds can be checked before implanting. A further problem with this method is that it requires the use of spacers. Spacers which are supplied loose suffer from the problems that they often have uneven, i.e. inconsistent lengths, they can have frayed ends, they swell if exposed to high humidity, they can pick up static charges if dry, they are not easy to see and their properties vary between suppliers.
In the second method, known from U.S. Pat. No. 5,860,909, individual seeds are implanted one at a time through a needle that is retracted in small steps out of the patient""s tissue, with a seed being deposited in the tissue after each retraction step. No spacers are required in this method as the spacing between the seeds is determined by the amount by which the needle is retracted after each seed is deposited. A commonly used device for performing the second method is called a xe2x80x9cMick Applicator(trademark)xe2x80x9d. In order to facilitate the handling of the individual seeds for use in a xe2x80x9cMick Applicator(trademark)xe2x80x9d, a plurality of seeds can be supplied pre-packaged in a plastic or stainless steel magazine called a xe2x80x9cMick Cartridge(trademark)xe2x80x9d. This method exposes the operator to less radiation, as the magazines provide substantial radiation shielding except directly in front of the opening in the front of the magazine. However this method has the disadvantage that the time spent in the operating theatre is longer than for the first method as each seed is individually implanted and the needle must be retracted a precise distance before the next seed is implanted. Additionally, it is difficult to confirm the spatial separation between the seeds. It is an object of the present invention to overcome some of the problems associated with the prior art methods and devices for implanting seeds.
According to the present invention, at least some of the problems with the prior art devices and methods for loading seed implant needles are solved by means of a loader device of the instant invention and the methods for using such devices to load seed implant needles. The device and its use makes it possible for an operator to quickly, easily and accurately prepare loaded seed needles for implantation while being exposed to a minimum dose of radiation.
The device desirably incorporates a spacer magazine which has the advantages that spacers are protected by the magazine, and the fact that a spacer fits into the spacer magazine is a guarantee that it fulfils at least some of the dimensional requirements placed on a spacer, i.e. it has a length less than the maximum permitted length and a diameter less than the maximum permitted diameter. The spacers are desirably biodegradable spacers and made of a synthetic, bioabsorbable material. The spacers in the spacer magazine are desirably sterile. Similarly, the seed magazine desirably contains seeds which are sterile and within sterile integrity packaging.
The present invention provides a loader device for loading seeds and spacers into a container. The loader includes a loader body defining a channel network including an elongate seed passageway, an elongate spacer passageway, and a dispenser passageway. The seed and spacer passageways extend respectively in fluid communication between a first open end and a first end of the dispenser passageway. The loader body also defines a dispense port in fluid communication with the dispense passageway. The loader body further defines a seed cartridge port for receiving a seed cartridge having a seed dispense port. The loader body includes means for aligning and positioning the seed dispense port in registry with one open end of the seed passageway. A spacer port is also provided in fluid communication with one end of the spacer passageway. A seed plunger causes dispensement of a seed from the seed cartridge into the open end of the seed passageway, whereby a seed dispensed from said seed cartridge passes through the seed passageway to the dispenser passageway.
The loader body may further define a spacer cartridge port for receiving a spacer cartridge having a spacer dispense port. The loader body would include means for aligning and positioning the spacer dispense port in registry with one open end of the spacer passageway. A spacer plunger causes dispensement of a spacer from the spacer cartridge into the open end of the spacer passageway, whereby a spacer dispensed from the spacer cartridge passes through the spacer passageway to the dispenser passageway.
The dispense port may further be defined by a container adaptor for removably receiving a container for accepting the seeds and the spacers passed into the dispenser passageway. The container may take the form of any useful holder for seeds or spacers including, for example, an elongate hollow needle. The loader body may further comprise a transparent window defining at least a portion of the channel network so as to allow visualization of the seeds and the spacers passed into the dispenser passageway.
The loader of the present invention may further comprise a releasable blocking means selectively positionable within the dispenser passageway. The releasable blocking means may be moved between a first position preventing the passage of any seeds and spacers within the dispenser passageway through said dispense port and a second position allowing passage of any seeds and spacers within the dispenser passageway through the dispense port. The combination of the window with a releasable blocking means allows a user to visually verify the proper order of an array of seeds and spacers prior to loading same into a hollow needle.
The present invention further contemplates providing a stand assembly for maintaining the loader body in an orientation permitting gravity-assisted passage of seeds and spacers through the dispense port. The stand assembly would also permit a user to load seeds and spacers without having to support the loader device themselves. The stand assembly includes a base member and an elongate leg member extending between the base member and the loader body. The stand assembly may further include a shield member movably mounted with respect to the leg member between a first position extending between a user and a container mounted to the container adaptor and a second position allowing a user access to the container mounted to the container adaptor. The stand assembly may further include a spillage retaining cup positioned on the base member in underlying registry with the dispense port or a container mounted on the loader so as to catch and retain any seeds or spacers inadvertently released from the loader or the container.
The present invention further provides a loader device for loading seeds and spacers into a container comprising a loader body defining a Y-shaped channel network opening at a dispenser port. One leg of the channel network includes a seed passageway extending between a seed insertion port and a dispenser passageway. The other leg of the channel network includes a spacer passageway extending between a spacer insertion port and the dispenser passageway. The dispenser port defines an open end of the dispenser passageway. The loader body may further define a container adaptor about the dispenser port for removably receiving a container for the seeds and spacers passing through channel network.
The present invention further provides a method for loading seeds and spacers comprising the steps of (i) providing a loader with a body, seed magazine receiving and locating means, seed dispensing means for ejecting seeds from a seed magazine, a seed-transporting path leading to a dispensing outlet, and a spacer-transporting path leading to a dispensing outlet, (ii) mounting a seed magazine containing one or more seeds in the seed transporting path and dispensing a seed through the dispensing outlet, (iii) placing a spacer in the spacer transporting path; and (iv) dispensing the spacer through the outlet. The method may further provide (v) providing said loader with a spacer magazine receiving and locating means, (vi) mounting a spacer magazine containing spacers in the spacer magazine receiving and locating means, (viii) ejecting a spacer into the spacer transporting path, and (ix) dispensing the spacer through the dispensing outlet.